Effect of Spoilage by Lipolytic Fungi Strains on Free Fatty Acids (FFA) Formation in Fermented and Dry Cocoa Beans

Abstract

Aim: High free fatty acids (FFA) content of cocoa beans is high lead to alter quality of butter fraction and chocolate manufactured. During primary post-harvest processing, cocoa beans harbor lipase producing mold speciess could trigger the accumulation of FFA. This study investigated the improvement of the quality of raw cocoa material sourced from Côte d’Ivoire regarding its high FFA concentration. Methods: Fermented and dry cocoa were sampled on-farm level in some main cocoa producing regions of Côte d'Ivoire. Contaminating mold strains were isolated using Sabouraud chloramphenicol agar incubated at 25°C for 7 days. Morphological identification of mold isolates was preformed from younger fungal culture. Biochemical study about lipolytic properties of mold isolates was carried out using Cazpeck-Dox Agar medium enriched with olive oil as carbon source and rhodamine B as indicator of lipase activity. Extraction, PCR amplification using a specific transcribed spacer primer (ITS4/ITS5) and sequencing of DNA were performed for fungal species molecular identification. Results: Approximately 154 mold isolates belonging to 8 genera were found in tested cocoa beans. Only Rhizopus oryzae, Absidia corymbifera, Mucor heimalis, Aspergillus niger, A. tubingensis, A. aculeatus, A. flavus, A.  tamari, A. fumigatus, Nigrospora sphaerica, Curvularia geniculate and Penicillium chrysogenum species produced greater lipolytic properties. A. corymbifera, A. niger, A. fumigatus and R. orysae were the most frequent and predominant species. Cocoa beans inoculated with R. oryzae, A. corymbifera or A. niger recorded higher FFA content above 1.75%. Conclusion: Reducing of the mold species growth during cocoa primary post-harvest processing could sustainably produce raw cocoa material with less FFA.